FIG. 1 is a circuit diagram of a common antenna switch. The antenna switch 10 comprises an antenna unit 11 and a plurality of switch units 13. One end of each switch unit 13 is connected to the antenna unit 11, and the other end of each switch unit 13 is connected to different transmitting/receiving terminals 15 to switch the connection of the antenna unit 11 and each transmitting/receiving terminal 15.
In actual application, one of switch units 13 is turned on, and other switch units 13 are turned off, and the antenna unit 11 is able to be electrically connected to one of transmitting/receiving terminals 15 via the on state switch unit 13. Thus, the RF signal received by the antenna unit 11 is able to be transmitted to the transmitting/receiving terminal 15 that is electrically connected to the antenna unit 11, or the RF signal can be transmitted from the transmitting/receiving terminal 15 to the antenna unit 11. Further, each transmitting/receiving terminal 15 may be used to transmit or receive RF signals with different frequency band.
However, the parasitic capacitance may be generated by each off state switch unit 13. Moreover, each off state switch unit 13 is connected in parallel to generate large parasitic capacitance. Thus, the insertion loss of the antenna switch 10 may be increased and may cause loss of the RF signal passing through the antenna switch 10.